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Design, Analysis and Experimental Performance of a Bionic Piezoelectric Rotary Actuator

Journal of Bionic Engineering 2017年第2期14卷 348-355页

作者： Shupeng Wang Weibin Rong Lefeng Wang Zhichao Pei Lining Sun State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150080 China

This study presents a piezoelectric rotary actuator which is equipped with a bionic driving mechanism imitating the cen- tipede foot. The configuration and the operational principle are introduced in detail. The movement model is established to analyze the motion of the actuator. We establish a set of experimental system and corresponding experiments are conducted to evaluate the characteristics of the prototype. The results indicate that the prototype can be operated stably step by step and all steps have high reproducibility. The driving resolutions in forward and backward motions are 2.31 grad and 1.83 μrad, respectively. The prototype can also output a relatively accurate circular motion and the maximum output torques in forward and backward directions are 76.4 Nmm and 70.6 Nmm, respectively. Under driving frequency of 1 Hz, the maximum angular velocities in forward and backward directions are 1029.3 grad·s^-1 and 1165 μrad·s^-1 when the driving voltage is 120 V. Under driving voltage of 60 V, the angular velocities in forward and backward motions can be up to 235100 grad·s^-1 and 153650 μrad·s^-1 when the driving frequency is 1024 Hz. We can obtain the satisfactory angular velocity by choosing a proper driving voltage and frequency for the actuator.

关键词： bionic foot piezoelectric rotary actuator centipede foot stick-slip

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Hybrid task priority-based motion control of a redundant free-floating space robot

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Chinese Journal of Aeronautics 2017年第6期30卷 2024-2033页

作者： Cheng ZHOU Minghe JIN Yechao LIU Zongwu XIE Hong LIU State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 China

This paper presents a novel hybrid task priority-based motion planning algorithm of a space robot. The satellite attitude control task is defined as the primary task, while the leastsquares-based non-strict task priority solution of the end-effector plus the multi-constraint task is viewed as the secondary task. Furthermore, a null-space task compensation strategy in the joint space is proposed to derive the combination of non-strict and strict task-priority motion planning,and this novel combination is termed hybrid task priority control. Thus, the secondary task is implemented in the primary task＇s null-space. Besides, the transition of the state of multiple constraints between activeness and inactiveness will only influence the end-effector task without any effect on the primary task. A set of numerical experiments made in a real-time simulation system under Linux/RTAI shows the validity and feasibility of the proposed methodology.

关键词： Base attitude control Hybrid task-priority Motion planning Multiple constraints Redundant space robot

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A Parallel Actuated Pantograph Leg for High-speed Locomotion

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Journal of Bionic Engineering 2017年第2期14卷 202-217页

作者： Wei Guo Changrong Cai Mantian Li Fusheng Zha Pengfei Wang Kenan Wang State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 China

High-speed running is one of the most important topics in the field of legged robots which requires strict constraints on structural design and control. To solve the problems of high acceleration, high energy consumption, high pace frequency and ground impact during high-speed movement, this paper presents a parallel actuated pantograph leg with an approximately decoupled configuration. The articulated leg features in light weight, high load capacity, high mechanical efficiency and structural stability. The similarity features of force and position between the control point and the foot are analyzed. The key design parameters, K1 and K2, which concern the dynamic performances, are carefully optimized by comprehensive evaluation of the leg inertia and mass within the maximum foot trajectory, A control strategy that incorporates virtual Spring Loaded Inverted Pendulum （SLIP） model and active force is also proposed to test the design. The strategy can implement highly flexible impedance without mechanical springs, which substantially simplifies the design and satisfies the variable stiffness requirements during high-speed running. The rationality of the structure and the effectiveness of the control law are validated by simulation and experiments.

关键词： high-speed parallel actuated pantograph leg optimization virtual SLIP model active force

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Design and Characterization of Magnetically Actuated Helical Swimmers at Submillimeter-scale

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Journal of Bionic Engineering 2017年第1期14卷 26-33页

作者： Lefeng Wang Huichao Xu Wenhe Zhai Bensong Huang Weibin Rong State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150080 China

Bacteria with helical flagella show an ideal mechanism to swim at low Reynolds number. For application of artificial mi- croswimmers, it is desirable to identify effects of structural and geometrical parameters on the swimming performance. In this study, a double-end helical swimmer is proposed based on the usual single-end helical one to improve the forward-backward motion symmetry, The propulsion model of the artificial helical microswimmer is described. Influences of each helix parameter on the swimming velocity and propulsion efficiency are further analyzed. The optimal design for achieving a maximum propulsion velocity of submillimeter scale swimmers is performed based on some constraints. An experimental setup consisting of three-pair of Helmholtz coils is built for the helical microswimmers. Experiments of microswimmers with several groups of parameters were performed, and the results show the validity of the analysis and design.

关键词： double-end helical microswimmers magnetic actuation swimming velocity optimal design

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Multi-optimizationofasphericalmechanismforminimallyinvasivesurgery

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Journal of Central South University 2017年第6期24卷 1406-1417页

作者： NIU Guo-jun PAN Bo ZHANG Fu-hai FENG Hai-bo FU Yi-li State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China

In order to obtain the remote center motion(RCM) mechanism with better performance indexes and avoid the collision of multi-manipulators in minimally invasive surgery(MIS), a novel multi-objective optimization model was presented. There were two optimization objectives: a global kinematic performance index and a comprehensive stiffness index. Other indexes to characterize the design requirements such as collision probability, workspace, mechanism parameter, mass, and wall thickness were considered as constraints. Angles between two adjacent joints and cross-section dimensions of links were chosen as the design variables. The non-dominated sorting genetic algorithm II(NSGA-II) was adopted to solve the complex multi-objective optimization problem. Then, a 3-degree of freedom(DoF) MIS robotic prototype based on optimization results has been built up. The experiments to test the spatial position change of the remote center point and to test the absolute position accuracy and repetitive position accuracy of the MIS robot were achieved, and the experimental results meet the requirements of MIS.

关键词： minimally invasive surgery medical robot multi-objective optimization remote centre motion

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Analysis of reaction torque-based control of a redundant free-floating space robot

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Chinese Journal of Aeronautics 2017年第5期30卷 1765-1776页

作者： Minghe JIN Cheng ZHOU Yechao LIU Hong LIU State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 China

Owing to the dynamics coupling between a free-floating base and a manipulator, the non-stationary base of a space robot will face the issue of base disturbance due to a manipulator＇s motion. The reaction torque acted on the satellite base＇s centroid is an important index to measure the satellite base＇s disturbance. In this paper, a comprehensive analysis of the reaction torque is made, and a novel way to derive the analytical form of the reaction torque is proposed. In addition,the reaction torque null-space is derived, in which the manipulator＇s joint motion is dynamically decoupled from the motion of the satellite base, and its novel expression demonstrates the equivalence between the reaction torque null-space and the reaction null-space. Furthermore, the reaction torque acted as an optimization index can be utilized to achieve satellite base disturbance minimization in the generalized Jacobian-based end-effector Cartesian path tracking task. Besides, supposing that the redundant degrees of freedom are abundant to achieve reaction torque-based active control, the reaction torque can be used to realize satellite base attitude control, that is, base attitude adjustment or maintenance. Moreover, because reaction torque-based control is a second-order control scheme, joint torque minimization can be regarded as the optimization task in reaction torque-based active or in-active control. A real-time simulation system of a 7-DOF space robot under Linux/RTAI is developed to verify and test the feasibility and reliability of the proposed ideas. Our extensive empirical results demonstrate that the corresponding analysis about the reaction torque is correct and the proposed methods are feasible.

关键词： Attitude control Base disturbance Dynamics modeling Reaction torque Real time simulator Space robot

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Simulation and Experiments on the Capillary Force between a Circular Disk and a Parallel Substrate

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Chinese Physics Letters 2017年第5期34卷 92-95页

作者：王乐锋黄本松何元哲荣伟彬孙立宁 State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150080

The capillary force of a liquid bridge with a pinned contact line between a small disk and a parallel plate is investigated by simulation and experiments. The numerical minimization simulation method is utilized to calculate the capillary force. The results show excellent agreement with the Young-Laplace equation method. An experimental setup is built to measure the capillary force. The experimental results indicate that the simulation results agree well with the measured forces at large separation distances, while some deviation may occur due to the transition from the advancing contact angle to the receding one at small distances. It is also found that the measured rupture distance is slightly larger than the simulation value due to the effect of the viscous interaction inside the liquid bridge.

关键词： Simulation and Experiments on the Capillary Force between a Circular Disk and a Parallel Substrate

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Local Pose optimization with an Attention-based Neural Network

Local Pose optimization with an Attention-based Neural Netwo...

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2019 IEEE/RSJ International Conference on Intelligent Robots and systems (IROS)

作者： Yiling Liu Hesheng Wang Fan Xu Yong Wang Weidong Chen Qirong Tang Department of Automation Shanghai Jiao Tong University Shanghai China State Key Laboratory of Robotics and System (HIT) Beijing Institute of Control Engineering Tongii University

In this paper, we propose a novel pose optimizer which can be inserted into either supervised or unsupervised end-to-end visual odometry for the purpose of local pose optimization. The pose optimizer is an analogue of the pose graph optimization used in traditional VSLAM algorithms. Local pose optimization is performed by an attention-based neural network which iteratively refines the predicted pose estimates of an image snippet. Instead of complicated graph convolutional network, the attention mechanism based on geometric consistency of trajectory constraint is utilized because pose features whose spatial distribution is not important can be flattened to vectors and then processed. The pose optimizer is aimed at improving pose estimation accuracy by redistributing errors of pose estimates. Quantitative and qualitative evaluation of the proposed approach on the KITTI Odometry dataset [1] is presented to demonstrate its effectiveness in improving pose estimation accuracy and minimizing pose drift.

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Singular Configuration Analysis of a Portable Exoskeleton Arm

Singular Configuration Analysis of a Portable Exoskeleton Ar...

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Chinese Automation Congress (CAC)

作者： Yongfei Xiao Xiaochun Fu Jie Zhao Qilu University of Technology(Shandong Academic of Science) Institute of Automation Jinan China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China

This paper focuses on the analysis and simulation of singularity configuration of the portable exoskeleton arm. Firstly, the kinematic equation and the Jacobian matrix are deduced. The singular configurations of the redundant exoskeleton mechanism are obtained in a manner that resolves the sub-determinant. Secondly, the comparison between the singular configurations of the exoskeleton arm is made by the simulation of the dexterity index to demonstrate the effectiveness. Finally, the advantages and disadvantages of various dexterity indicators are analyzed in the light of the simulation results and the singular configurations. Simulation results of different dexterity indicators verified the correctness of the singularity analysis. The proposed method is helpful for the further trajectory planning research and singularity avoidance research of exoskeleton arm.

关键词： Jacobian matrices Manipulators Exoskeletons Indexes Ellipsoids Mathematical model Kinematics

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A Local Dynamic Path Planning Approach for WMRs Based on Fuzzy Dual CHOMP

A Local Dynamic Path Planning Approach for WMRs Based on Fuz...

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IEEE International Conference on Cyber Technology in Automation, Control, and Intelligent systems

作者： Zhi Li Liang Ding Bo You Haibo Gao Mechanical & Power Engineering College Harbin University of Science and Technology Harbin China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China

ISBN: (数字)9781728107707

ISBN: (纸本)9781728107714

Wheeled mobile robots (WMRs) are widely utilized in exploration tasks on different planets. The path planning technique is required to guide a WMR to a target point or region. A new path planning method in a dynamic environment is proposed. The method improves the original dual Covariant Hamiltonian Optimization for Motion Planning (CHOMP) method by a fuzzy reasoning module and Nonmonotone Gradient Projection Algorithm (NGPA). Thus, this method can achieve low cost paths while maintaining the accessibility of each path nodes. The method to establish local dynamic cost map based on a new velocity-based artificial potential field (VAPF) is proposed as the environment for path planning. Thus, the low cost paths can guide a WMR away from obstacles. Results of the simulations show that the path planning method can dynamically generate a smooth path for a WMR to avoid obstacles.

关键词： Path planning Fuzzy reasoning Task analysis Mobile robots Cost function Planets

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